POS1228 DETERMINANTS OF PATIENT GLOBAL DISEASE ACTIVITY IN ADULT MYOSITIS
Authors: S. Keret, D. Saygin, C. V. Oddis, S. Moghadam-Kia, R. Aggarwal
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Myositis is a heterogeneous rare autoimmune disorder with muscle weakness and many systemic features that contribute to morbidity and mortality. The myositis core set measures (CSM) were developed to capture myositis disease activity, and are useful in clinical practice and therapeutic trials [<b>1].</b> However, the CSM are primarily subjective physician assessments. Understanding the drivers of the patient global (PT global) disease activity assessment and the difference between the physician and patient perception of their disease activity is important to elucidate [<b>2].</b> <h3>Objectives</h3> To examine the determinants of the PT global, and the discordance between PT global and physician-global (MD global) disease activity in myositis. <h3>Methods</h3> Adults with myositis were enrolled at the University of Pittsburgh Myositis Center and the following outcome measures were collected: Manual muscle testing (MMT), HAQ, creatine kinase (CK), fatigue, pain, PROMIS physical function (PF-20), Short Form-36 (SF-36), sit-to-stand, timed up-and-go, six-minute walk, and Actigraph step per min/day count. PT- and MD global scores (10cm visual analog scale [VAS]) were recorded, and discordance was defined as ≥3 point difference between the scores based on published literature in other rheumatic diseases [<b>3].</b> The difference in both scores was also analyzed in myositis subjects with active vs inactive disease. A linear regression model was used to determine the contribution of each measure to the PT global. <h3>Results</h3> Fifty patients (60% females; mean age 51.6 [±14.9] years) with probable/definite myositis (24 dermatomyositis [DM], 6 polymyositis [PM], 9 necrotizing myositis [NM] and 11 anti-synthetase syndrome [ASyn]) according to the ACR/EULAR Classification Criteria were enrolled prospectively. PT global correlated strongly with muscle disease activity, MD global, MMT, HAQ-DI, PROMIS physical function, pain VAS, fatigue VAS, SF36 physical function, health, fatigue, social functioning, and pain subdomains, 6MWD and step per min/day count (r=0.57-0.75), moderately with STS, TUG and CK levels (r=0.36-0.46), and poorly with cutaneous, pulmonary, and extra-muscular disease activity (r=0.02-0.17). Correlations of PT global with pain, physical function, fatigue, quality of life and physical activity measures were overall stronger than the MD global, as opposed to muscle and extra-muscular disease activity which correlated better with the MD global. Physical function and fatigue measures contributed most to the PT global, followed by measures of pain, physical activity, quality of life, and muscle disease, while the MD global was primarily driven by muscle disease activity (<b>Figure 1</b>). The PT global was discordant with MD global in 30% (n=15) of the patients, where the PT global was higher than the MD global in 66% (n=10). Patients with a discordantly high PT global suffered from significantly higher levels of pain (p=0.03), fatigue (p=0.05), and more functional limitation as reflected by the HAQ (p=0.04). <h3>Conclusion</h3> Fatigue, pain, and physical activity are important driving factors of the differences observed in the patient vs. physician assessment of myositis disease activity. Understanding the gap between patient-physician perspectives may help provide patient-centered care. <h3>References</h3> [1]Rider LG, Aggarwal R, Machado PM, et al. Update on outcome assessment in myositis. Nat Rev Rheumatol. 2018;14:303-318. [2]Smolen JS, Strand V, Koenig AS, Szumski A, Kotak S, Jones TV. Discordance between patient and physician assessments of global disease activity in rheumatoid arthritis and association with work productivity. Arthritis Res Ther. 2016;18:114. [3]Desthieux C, Hermet A, Granger B, Fautrel B, Gossec L. Patient-Physician Discordance in Global Assessment in Rheumatoid Arthritis: A Systematic Literature Review With Meta-Analysis. Arthritis Care Res (Hoboken). 2016;68:1767-1773. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Shiri Keret: None declared, Didem Saygin: None declared, Chester V Oddis: None declared, Siamak Moghadam-Kia: None declared, Rohit Aggarwal Consultant of: Mallinckrodt, Octapharma, CSL Behring, Bristol. Myers-Squibb, EMD Serono, Q32, Kezar, Pfizer, AstraZeneca, Alexion, Argenx, Boehringer Ingelheim (BI), Corbus, Janssen, Kyverna, Roivant, Merck, Galapagos, Actigraph, Scipher, Horizon Therapeutics, Teva, Beigene, ANI Pharmaceuticals, Biogen, Nuvig, Capella Bioscience, CabalettaBio., Grant/research support from: Mallinckrodt, Pfizer, Bristol Myers-Squibb, Q32, EMD Serono, Janssen, Boehringer Ingelheim (BI)